Reproduction in humans 2

Ovulation

When an egg is released from the ovary

Functions of the placenta

Allowed to obtain oxygen and glucose from the blood, get rid of carbon dioxide and urea, secretes oestrogen and progesterone to prevent abortion

Amnion

A membrane that encloses the embryo

Amniotic fluid

Protects the embryo from damage

First stage of birth

Dilation of the cervix to allow the baby to pass through. Muscles of the uterus contract and tear the amnion letting out the amniotic fluid

Second stage of birth

Strong contractions of the uterus push the baby out

Third stage of birth

After the baby has been born, the uterus continues to contract to push the placenta out

Sexually immature

Unable to reproduce

Developments that happen during puberty

The gametes start to mature and be released, the bodies adapt to allow reproduction

FSH and LH in boys

FSH stimulates sperm production, LH in instructs the testes to secrete testosterone

Males secondary sexual characteristics

Growth of the testes and penis, growth of body hair, muscle development, breaking of the voice

FSH and LH in girls

FSH stimulates the maturation of an ovum, LH promotes ovulation

Female secondary sexual characteristics

Growth of body hair, breast development, beginning of menstruation, development of rounded hips, voice deepens, sexual drive develops

How long is a menstrual cycle

28 days

When does ovulation happen

14 day

What is the purpose of menstrual cycle

To control the development of the lining so that if the egg is fertilised it will be ready to receive the egg

Follicle

Non mature egg

What happens at day 14

Follicle moves towards the edge of the ovary and the egg is released as the follicle bursts open

Progesterone in the menstrual cycle

Produced by the corpus luteum, prevents or inhibits the release of FSH and LH, maintains the thickening of the uterus lining

Oestrogen in the menstrual cycle

Produced under the influence of FSH and LH, promotes the thickening of the uterus lining

LH in the menstrual cycle

Causes ovulation

FSH in the menstrual cycle

Promotes the maturation of the follicles

Corpus luteum (controlled by LH)

A large yellow swelling in an ovary after the egg has been released

Oestrogen in relationship with FSH and LH

Slows down the production of LH and FSH

What happens to corpus luteum if the egg is not fertilised

It breaks down